POTTERTON SUPRIMA 40L

[andyandy2]

I've read numerous posts on here about potterton boilers and pcb problems, my problem is HW ok but no CH ( or it will occasionally fire up) i've no handbook with the boiler and just want to make sure that it is not a fault with the controller or roomstat, is there an easy way to by-pass these to see if the boiler fires up, before i start messing with the pcb Thanks

 

[Ethelred]

If it is a Y plan then check the 3 port valve microswitches as the valve is not energised for HW only.
If you have CH and HW on does the HW work and the CH not work. a sure sign of a faulty 3 port valve.

Cheers

 

[baxpoti]

.......or a faulty room stat

 

[andyandy2]

i've not got any handbook or wiring diagram can i by-pass the room stat easily, i think from memory its got three wires red yellow blue

 

[baxpoti]

Blue would normally be the Neutral.
Link red and yellow.

 

[Vic Spanner]

I've read numerous posts on here about potterton boilers and pcb problems,

News to me have i missed something in the last 10 years or have i been dreaming.

 

[andyandy2]

I'm still having problems with no heating, (hot water ok) when i switch on hot water red light on boiler goes out and green comes on flashing, when i switch on heating red light stays on, I've by-passed the room stat, and changed the controller (switch seemed faulty anyway) I've checked the pump spindle is free, if i operate the lever on the motorised valve manually the pump seems to run for about a minute but nothing gets hot, not sure what type the motorised valve is, (difficult to get to) put it doesn't seem to have the notch position on the manual lever, Any help would be much appreciated before i call in the experts Thanks

 

[gas4you]

Is it a 3 port or 2 2 port valves you have. Still sounds like the heating side of this is faulty. Change valve head. Boiler does not know what or where call for heat is coming from as doesn't the pump, so it would fail for heating and hot water if it was pcb etc.

 

[MANDATE]

I agree it certainly sounds like a motorised valve problem.
assuming it's a 3 port.
You need to verify the room stat is not the problem by checking voltage on the valves white wire.
Valve problems can be either stuck valve spindle, failed motor so valve does not move across to CH only position, or failed microswitch so even if valve does move to CH only positon, the failed microswitch prevents boiler from lighting.
suggest you search for 3 port motorised valve on this forum, there is considerable information on this common problem.